1. Field of the Invention
This invention relates to electrochemical cells and specifically to lead acid storage batteries.
2. Discussion of the Prior Art
There are five persistent engineering problems which have plagued the lead/acid storage battery industry since the inception of multi-cell batteries. The first problem has been defective intercell connections. Presently, intercell connections are made by welding together two plate strap upstanding lugs through a hole in a partition of a battery container. This welded connection is commonly known as a "through the partition" connection. One problem with this conventional "through the partition" connection is that the weld is susceptible to breakage. Broken connections will allow electrical arcing. An explosion may occur when electrical arcing ignites hydrogen and oxygen gasses which are naturally generated inside the battery.
Battery explosions are often serious and sometimes lethal. According to National Highway Traffic and Safety Administration statistics, 6,000 battery related injuries are treated annually in hospitals. Currently, a conventionally built 12 volt battery has five internal "through the partition" weld connections plus two external terminal weld connections. All of these weld connections have the potential to break, electrically arc, and cause an explosion.
The second problem relates to the seal at the intercell connections between adjacent plate strap mold wells. A good seal is important to prevent electrolyte from leaking from one cell to another. Electrolyte leakage can cause cells to electrically discharge and become electrically unbalanced.
The third problem of conventionally built batteries is electrolyte leakage in the area of the external terminals. In conventional construction, hollow external terminal bushings are pre-cast of lead and molded into the battery cover. After the battery cover is heat sealed to the battery container, internal posts extending from two end cells in the battery container--one positive and one negative--protrude through the two hollow external terminal bushings in the battery cover. The ends of the internal posts and the pre-cast external terminal bushings are connected together by a welding process. The hollow external terminal bushings molded into the cover are intended to seal the external terminal from electrolyte and gas leakage from the battery. The hollow external terminal bushing does provide some improvement over rubber gaskets, "O" rings, lock nuts, and other means used in the past to prevent electrolyte leakage. However, hollow external terminal bushings, besides being costly, are relatively fragile and depend on a good weld to the internal cell posts and are still prone to gas and electrolyte leakage.
The fourth problem is corrosion at the fusion juncture of the plate lugs to the plate straps. The corrosion is caused by acids and corrosive gasses attacking combinations of lead alloys used in the battery.
The fifth problem is the necessity of brushing plate lugs before entry into the molten plate strap. The brushing removes foreign material such as lead oxide residue left from the plate pasting operation and any lead oxide derived from the natural exposure to the atmosphere. Brushing also creates a bright metal appearance on the plate lug.
Accordingly, there is a clearly felt need in the art to eliminate the bane of explosions due to weld failures. There is a further need to eliminate pre-molded external terminal bushings, pre-molded internal cell posts, and associated welding procedures for making external terminals. There is yet a further need to preclude acids and corrosive gasses from reaching the fusion juncture between the battery plates and straps. There is finally a need to eliminate the need to brush a battery plate lug before insertion into a molten plate strap.